So, why do some horses develop food allergies?
In order for a horse to have an allergic reaction to food, potential allergens must pass through the intestinal mucosa. The mucosa is the membrane that lines the intestinal tract. In a healthy gut, the smaller potential allergens are glommed together with Immunoglobulin-A making the antigens too large to pass through the mucosa. In a gut that is not functioning properly, these small antigens escape. This is sometimes referred to as Leaky Gut Syndrome.
Approximately 70% of white blood cells pass through the gut. If the gut is leaking antigens it will pass into this blood supply. As the antigens are introduced to the immune system it recognizes them by their protein and adverse food reactions or allergic reactions can take place. Antibodies attach themselves to the allergens, then a complex protein attaches itself. This starts a chain reaction of complex proteins attaching to the surface of mast cells. At the end of this chain reaction the cell may be destroyed and in allergic episodes the cells involved are called mast cells. These cells carry large stores of histamine and other allergic mediators that eventually cause the allergic symptoms.
Horses rely on bacteria to digest or break down plant materials into small units that can be absorbed and utilized by the body. A healthy intestinal tract has a large population of these normal bacteria, which are collectively referred to as their “intestinal flora.” A normal intestinal mucosa or lining secretes an adequate amount of protective mucus which acts as a “barrier” that keeps the bacteria confined to the lumen or inside of the intestine, thus protecting the body.
A horse’s gut health can be negatively affected by naturally occurring biological issues and by foreign elements introduced into the digestive tract. Young horses may not have a fully developed mucosa making it possible for antigens to pass through. Older horses many have other autoimmune disorders or medical conditions that cause poor gut health allowing for leakage. Foreign elements would include anti-inflammatory drugs such as bute, antibiotics, and ant-acids. Bute reduces the production of mucus production that the gut uses to block antigens. Antibiotics decrease the levels of healthy bacteria (flora) and treating ulcers with antacids upsets the acid alkaline balance in the gut making it a less then optimal environment for healthy bacteria to thrive.
Determining What a Horse is Allergic Too
Determining what a horse is allergic to can be difficult and if it is a food allergy it can also be time consuming. One common method is a serum allergy test. This test looks for allergic reactions from grasses, weeds, trees, fungi, epidermal, house dust, foods, indoor elements (shavings, cotton. ect), insects and grains.
Symptoms of Adverse Food Reactions (Allergies)
- Itchy watery eyes or nose
- Wheezing caused by swelling of the airway
- Hives, or all over body itching
- Ruling out Other Causes
Many of the symptoms associated with an allergic food reaction are synonymous with systems of other illnesses or diseases. It is important to seek the attention of your veterinarian to rule out other possible causes.
Learn More: Horse With A Food Allergy: Kemo
Learn More: Supplement To Support Equine Gut Health